1. Field of the Invention
The present invention relates to a light illumination apparatus and a liquid crystal display apparatus using the same.
2. Description of the Prior Art
Liquid crystal display devices having the merit of thinness and low electric power consumption have been applied in recent years to a display system mainly treating motion pictures, such as television receivers, and use thereof is being further enlarged.
Recently, however, there has reported the problem of deterioration of motion picture quality peculiar to hold type display devices represented by liquid crystal display devices (the Institute of Electronics, Information and Communication Engineers (IEICE) Technical Report SID96-4, pp.19-26 (1996-06)). The report also shows that a method of multiplying frame frequency by n, a method in which picture is displayed for {fraction (1/n)} of frame period and black is displayed for the remainder of the frame period, and the like are useful for solving the problem of deterioration of motion picture quality. The effectiveness of these methods for high-speed motion picture display is increased as the value of n increases.
In consideration of the above problem, technical developments corresponding to the quality of motion picture (hereinafter referred to as xe2x80x9cmotion picture qualityxe2x80x9d) in liquid crystal display devices have been carried out. As a technology for improving motion picture quality by use of a light illumination apparatus, Japanese Patent Laid-Open No. Sho 64-82019 discloses a motion picture quality improving technology relating to blanking display in which a light-emitting portion of a backlight is blinked in accordance with picture driving scan.
Besides, apart from motion picture quality improving technology, a flat plate type light illumination apparatus providing illumination while changing the optical characteristics of predetermined regions of light-pipes in accordance with display, in order to enhance luminance, has been disclosed in Japanese Patent Laid-Open No. Hei 11-249580.
However, in the technology disclosed in the Japanese Patent Laid-Open No. Sho 64-82019, blanking can be controlled only by the unit of lamp diameter. Namely, blanking cannot be set with optimum timing for each scanning line, and there is still the problem that nonuniformity of luminance is generated between lamps. Although this problem can be solved by increasing the number of lamps, the lamps themselves actually have a diameter of not less than 1.8 mm and, therefore, it is impossible now to carry out blanking with the width on the order of pixels (about several tens of micrometers). Further, the number of lamps and the number of inverters for driving the lamps are extremely increased, which leads to a new problem of high cost.
On the other hand, the light illumination apparatus for illuminating predetermined regions as disclosed in the Japanese Patent Laid-Open No. Hei 11-249580 is useful in the point of concentrating the light incident on light-pipes, but still have problems yet to be solved in order to realize light utility efficiency and uniformity. In addition, the patent publication does not have any description about a driving method corresponding to display of motion picture, so there are still problems to be solved for realizing a light illumination apparatus adapted for motion pictures.
In view of the above situations, it is an object of the present invention to provide a light illumination apparatus with high light utility efficiency or uniformity and a liquid crystal display apparatus capable of displaying pictures with good motion picture quality using the light illumination apparatus.
In accordance with an aspect of the present invention, there is provided a light illumination apparatus comprising: a pair of light-pipes; and a liquid crystal layer sandwiched between the pair of light-pipes; the light illumination apparatus further comprising: a first transparent electrode divided into a plurality of regions disposed on the side of one of the pair of light-pipes faced to the liquid crystal layer; a second transparent electrode disposed on the side of the other light-pipe faced to the liquid crystal layer; a light source disposed on a lateral side of at least one of the pair of light-pipes; and a first reflector disposed on the side of either one of the pair of light-pipes opposite to the side faced to the liquid crystal layer, with an air layer therebetween; wherein the light-pipe attended by the light source has a refractive index of not less than {square root over ( )}2, whereby totally internal reflection can be utilized and a light illumination apparatus with high light utility efficiency and low electric power consumption can be obtained.
In accordance with another aspect of the present invention, there is provided a liquid crystal display apparatus comprising: a liquid crystal display device comprising a pair of substrates, a first liquid crystal layer sandwiched between the pair of substrates, and a liquid crystal display device driving circuit for driving the liquid crystal layer; and a light illumination apparatus comprising a pair of light-pipes, a second liquid crystal layer sandwiched between the pair of light-pipes, and a backlight driving circuit for driving the liquid crystal layer, wherein driving mode of the first liquid crystal layer is normally open while driving mode of the second liquid crystal layer is normally transmissive, or driving mode of the first liquid crystal layer is normally closed while driving mode of the second liquid crystal layer is normally scattering, whereby the profile of brightness of light sensed by the observer can be made steep, and a liquid crystal display apparatus with high light utility efficiency and high contrast ratio can be obtained.
In accordance with a further aspect of the present invention, there is provided a liquid crystal display apparatus comprising: a liquid crystal display device comprising a plurality of pixels, and a driving circuit portion for controlling the display of the plurality of pixels; a light illumination apparatus; and a backlight driving circuit portion for controlling the light illumination apparatus, wherein the liquid crystal display device further comprises a liquid crystal display controller for controlling the driving circuit portion in the liquid crystal display device and the backlight driving circuit portion in the light illumination apparatus, in accordance with inputted picture data; the light illumination apparatus is a light illumination apparatus comprising the first transparent electrode in the form of stripes is composed of n transparent electrode stripes according to the present invention; and where the period of time for which the liquid crystal display controller performs display on the pixels in the liquid crystal display device is {fraction (1/k)} of one frame period, the number of the first transparent electrode stripes selected as scattering condition at a time is not more than {fraction (n/k)}, and k is determined for every frame period, whereby the brightness of light sensed by the observer in one frame period can be made constant even in the case of so-called {fraction (1/n)} fold speed driving, and a liquid crystal display apparatus having high light utility efficiency and adapted for display of motion picture with high quality can be obtained.
Besides, it is possible to provide a blink light illumination apparatus with high light utility efficiency. In addition, by use of the blink light illumination apparatus, an active matrix type liquid crystal display apparatus capable of obtaining good display characteristics even in the case of displaying motion pictures with high moving speeds can be provided.
The above and other objects, features and advantages of the present invention will become apparent from the following description and appended claims, taken in conjunction with the accompanying drawings which show by way of example some preferred embodiments of the invention.